Message types
[Messaging basics]
Detailed Description
The Player message types.
| #define | PLAYER_MSGTYPE_DATA 1 |
| A data message. | |
| #define | PLAYER_MSGTYPE_CMD 2 |
| A command message. | |
| #define | PLAYER_MSGTYPE_REQ 3 |
| A request message. | |
| #define | PLAYER_MSGTYPE_RESP_ACK 4 |
| A positive response message. | |
| #define | PLAYER_MSGTYPE_SYNCH 5 |
| A synch message. | |
| #define | PLAYER_MSGTYPE_RESP_NACK 6 |
| A negative response message. |
Define Documentation
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A command message. Such messages are asynchronously published to devices, and are usually used to change some aspect of the device's state. |
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A data message. Such messages are asynchronously published from devices, and are usually used to reflect some part of the device's state. |
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A request message. Such messages are published synchronously to devices, usually to get or set some aspect of the device's state that is not available in data or command messages. Every request message gets a response message (either PLAYER_MSGTYPE_RESP_ACK or PLAYER_MSGTYPE_RESP_NACK). |
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A positive response message. Such messages are published in response to a PLAYER_MSGTYPE_REQ. This message indicates that the underlying driver received, interpreted, and processed the request. Any requested data is in the body of this response message. |
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A negative response message. Such messages are published in response to a PLAYER_MSGTYPE_REQ. This messages indicates that the underlying driver did not process the message. Possible causes include: the driver's message queue was full, the driver failed to interpret the request, or the the driver does not support the request. This message will have no data in the body. |
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A synch message. Only used in PLAYER_DATAMODE_PULL mode. Sent at the end of the set of messages that are sent in response to a PLAYER_PLAYER_REQ_DATA request. |